The long-term objective of this Core is to elucidate the molecular mechanisms underlying the biological responses to non-genotoxic environmental agents. The aims of the Core are: 1) to delineate signal transduction pathways and their effector components in various model systems: 2) to study the molecular mechanisms associated with the disruption of pathways, effectors, or signal transmission as a consequence of exposure to environmental agents; and 3) to determine how variations in genetic background affect normal signal transduction pathways. The specific hypothesis to be addressed is that certain environmental agents act to modify gene expression by interfering with the normal control mechanisms that regulate tissue-specific receptors and effector molecules, production of second messengers, and synthesis and activation of transcription factors. The research conducted by the members of this Core, from four different departments, are addressing these issues.